package cn.itcast.domain;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;

public class RandomValidateCode {

        public static final String RANDOMCODEKEY = "randomcode_key";//放到session中的key
        private Random random = new Random();
        private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串

        private int width = 80;//图片宽
        private int height = 26;//图片高
        private int lineSize = 40;//干扰线数量
        private int stringNum = 4;//随机产生字符数量

        /**
         * 生成随机图片
         */
        public void getRandcode(HttpServletRequest request,
                                HttpServletResponse response) {
            HttpSession session = request.getSession();
            //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
            BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
            //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
            Graphics g = image.getGraphics();
            g.fillRect(0, 0, width, height);
            g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE,18));
            g.setColor(getRandColor(160, 200));
            //绘制干扰线
            for(int i=0;i<=lineSize;i++){
                drowLine(g);
            }
            //绘制随机字符
            String randomString = "";
            for(int i=1;i<=stringNum;i++){
                randomString=drowString(g,randomString,i);
            }
            session.removeAttribute(RANDOMCODEKEY);
            session.setAttribute(RANDOMCODEKEY, randomString);
            g.dispose();
            try {
                //将内存中的图片通过流动形式输出到客户端
                ImageIO.write(image, "JPG", response.getOutputStream());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        /*
         * 获得字体
         */
        private Font getFont(){
            return new Font("Fixedsys",Font.CENTER_BASELINE,18);
        }
        /*
         * 获得颜色
         */
        private Color getRandColor(int fc,int bc){
            if(fc > 255)
                fc = 255;
            if(bc > 255)
                bc = 255;
            int r = fc + random.nextInt(bc-fc-16);
            int g = fc + random.nextInt(bc-fc-14);
            int b = fc + random.nextInt(bc-fc-18);
            return new Color(r,g,b);
        }

        /*
         * 绘制字符串
         */
        private String drowString(Graphics g,String randomString,int i){
            g.setFont(getFont());
            g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
            String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
            randomString +=rand;
            g.translate(random.nextInt(3), random.nextInt(3));
            g.drawString(rand, 13*i, 16);
            return randomString;
        }
        /*
         * 绘制干扰线
         */
        private void drowLine(Graphics g){
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(13);
            int yl = random.nextInt(15);
            g.drawLine(x, y, x+xl, y+yl);
        }
        /*
         * 获取随机的字符
         */
        public String getRandomString(int num){
            return String.valueOf(randString.charAt(num));
        }

}
